A master controller for instructing a control device that controls the motor of a railroad vehicle, for example, has been proposed (for example, see JP 2014-18053 A (PTL 1), JP H11-215616 A (PTL 2), and “Toyo Denki Seizo Technical Report”, Toyo Denki Seizo K. K., March 2011, No. 123, p. 36 (NPL 1)).
For example, FIG. 4 is a schematic cross-sectional diagram of a typical master controller for a railroad vehicle. The body 107 of the master controller illustrated in FIG. 4 has six positions (notch positions), “off” and “1” to “5”, that are selected by the driver operating a handle 103. The body 107 is connected to a control device load via a connector 104 and a cable 105. The body 107 includes a plurality of cams 102a to 102f that can turn in conjunction with operation of the handle 103.
FIG. 5 is a schematic right side view of the master controller in FIG. 4. As illustrated in FIG. 5, for example when a projection 108 formed on a cam 102f contacts a cam switch 101f, an input signal is transmitted via the cam switch 101f. In this way, cam switches 101a to 101f are provided in correspondence with the cams 102a to 102f. 
FIG. 6 is a circuit diagram of the master controller illustrated in FIG. 3. The locations where the handle positions are surrounded by trapezoids in the “cam development view” of FIG. 6 indicate that the cam(s) and cam switch(es) corresponding to the position of the handle 103 are in contact, and that one or more input signals are transmitted via the cam switch(es). For example, when the handle 103 is in the location corresponding to the “off” position, the cam switch 101a is closed (connected), and the other cam switches 101b to 101f are open (disconnected). When the handle 103 is in other positions as well, the cam switches 101a to 101f similarly open and close in accordance with the position.
The cam switches 101a to 101f are connected to a control device (load) of the vehicle via the connector 104 and the cable 105. The number of signals output from the connector 104 is equivalent to the number of the cam switches 101a to 101f. In the example illustrated here, six different signals are output.
In a typical master controller, such as the one provided in a large vehicle, a large current capacity is necessary for the cam switches 101a to 101f. 